Ukrainian President Volodymyr Zelenskyy has told the UN Security Council that Russian military must be brought to justice immediately for war crimes.

In a harrowing account, Mr Zelenskyy accused the Kremlin's troops of committing the worst atrocities since the Second World War.

He appeared at the meeting, convened by Britain, via video link and said civilians had been shot in the back after being tortured, crushed to death by tanks while in their cars and had been blown up with grenades while in their homes.

It comes after further evidence of civilian deaths has emerged over the past several days in areas of Ukraine previously under Russian occupation.

Russian troops retreated from areas outside Kyiv, before journalists and Ukrainians visited many towns and villages and discovered shallow and mass graves and other harrowing evidence of abuses.

Mr Zelenskyy told council members about some of the atrocities in his country, which he claims happened at the hands of the Russians.

Russia denies claims of civilian killings, accusing Ukraine of planting bodies after their withdrawal.

Mr Zelenskyy said: "They cut off limbs, cut their throats. Women were raped and killed in front of their children. Their tongues were pulled out only because their aggressor did not hear what they wanted to hear from them.

"Anyone who has given criminal orders and carried them out by killing our people will be brought before the tribunal which should be similar to the Nuremberg tribunals."

Images of civilian deaths and killings,particularly from the town of Bucha outside Kyiv, have stirred global revulsion and led to demands for tougher sanctions and war crime charges.

Making his first appearance before the UN's highest body, Mr Zelensky said the Russian troops are no different from other terrorists like the so-called Islamic State group. He showed the council brief video footage of bloody corpses that ended with the words "Stop Russian Aggression".

He stressed that Bucha was only one place and there are more with similar horrors, and called for a tribunal similar to the one set up at Nuremberg to try war criminals after the Second World War.

The grisly scenes of battered and burned bodies and evidence that some of the dead were bound and shot in the head have led western nations to expel dozens more of Moscow's diplomats and propose further sanctions, including a ban on coal imports from Russia.

The head of Nato warned that Russia is regrouping its forces to deploy them to eastern and southern Ukraine for a "crucial phase of the war", and said more horrors may come to light as Russian troops continue to pull back in the north.

"When and if they withdraw their troops and Ukrainian troops take over, I'm afraid they will see more mass graves, more atrocities and more examples of of war crimes," secretary-general Jens Stoltenberg said.

Ukrainian officials said the bodies of at least 410 civilians have been found in towns around Kyiv that were recaptured from Russian forces and a "torture chamber" was discovered in Bucha.

Mr Zelensky told the Security Council there was "not a single crime" that Russian troops had not committed in Bucha.

"The Russian military searched for and purposefully killed anyone who served our country. They shot and killed women outside their houses when they just tried to call someone who is alive. They killed entire families, adults and children, and they tried to burn the bodies," he said.

Police and other investigators walked the silent streets of Bucha on Tuesday, taking notes on bodies.

Associated Press journalists in the town counted dozens of corpses in civilian clothes. Many appeared to have been shot at close range, and some had their hands bound or their flesh burned. A mass grave in a churchyard held bodies wrapped in plastic.

The Kremlin denounced the images as fake and suggested the scenes were staged by the Ukrainians, but high-resolution satellite imagery from Maxar Technologies showed that many of the bodies had been lying in the open for weeks, during the time Russian forces were in the town.

US secretary of state Antony Blinken said the images from Bucha revealed "a deliberate campaign to kill, to torture, to rape, to commit atrocities". He said the reports were "more than credible" and the US and other countries will seek to hold the culprits accountable.

As western leaders condemned the killings in Bucha, Italy, Spain and Denmark expelled dozens of Russian diplomats, following moves by Germany and France. Hundreds of Russian diplomats have been sent home since the start of the invasion, many accused of being spies.

Kremlin spokesman Dmitry Peskov called the expulsions a "short-sighted" measure that would complicate communication and warned they would be met with "reciprocal steps".

The UK, however, has not expelled its Russian ambassador, with fresh calls being made yesterday by Labour for the government to do so.David Lammy MP, the shadow Foreign Secretary said: "There should be no place for Russia’s ambassador to parrot the regime’s lies or intelligence agents to continue their hostile activity in the UK."